This invention relates generally to irrigation water sprinklers of the type having a sprinkler spray head driven rotatably through a full- or adjustably set part-circle path, and particularly of the type having rotary drive components encased within a substantially closed sprinkler housing concealed from exposure to wind, sand, and the like. More specifically, this invention relates to an irrigation sprinkler including an improved reversing trip mechanism designed to accommodate forced maladjustment without component breakage or deviation from a preset adjustment condition, and further including water flow regulation means for improved control over spray head rotary speed regardless of water pressure or spray head nozzle size.
A wide variety of irrigation water sprinklers are known in the art for projecting or spraying a stream of water over a prescribed adjacent terrain area to irrigate lawns, gardens, crops, and the like. Many such sprinklers include a so-called fixed spray head or nozzle from which irrigation water is projected in a stationary pattern, whereas other known sprinkler designs include a rotary drive mechanism for driving a spray head or nozzle typically in a succession of relatively small incremental steps through a full- or reversible part-circle rotation thereby displacing the projected water spray in a stepwise manner over a full- or part-circle terrain area. In both types of sprinklers, the sprinkler spray head is frequently mounted at the upper end of a so-called pop-up stem designed to move the spray head from a retracted position stored within a sprinkler housing to an elevated spraying position when water under pressure is supplied to the sprinkler housing.
Impact drive sprinklers comprise one particularly common type of irrigation sprinkler designed for rotary drive and/or pressure responsive pop-up operation. See, for example, the rotary drive pop-up sprinkler shown and described in U.S. Pat. No. 4,182,494. In such sprinklers, an impact drive arm is biased by a spring for oscillatory swinging movement of a deflector unit into repeated interrupting engagement with a water stream discharged from a spray nozzle to impact a sprinkler body in a manner driving the sprinkler through a succession of small rotational steps. Reversing mechanisms are commonly included in such sprinklers to alter the direction of impact drive forces and thereby permit reversible rotation between set end limits of an arcuate part-circle path. However, while impact drive sprinklers of this general type are widely used with highly satisfactory results, the rotary drive and reversing mechanism components are necessarily exposed to the elements including sun, wind, precipitation, sand, grit, and the like. In some environments, this exposure can adversely affect operation and/or contribute to premature failure of the rotary drive or reversing mechanism components. Alternately, such exposure of the sprinkler components renders the sprinkler especially susceptible to unauthorized tampering by vandals including, for example, jamming of rotary drive components or adjustment of part-circle path end limits so that water is sprayed onto unintended areas.
Accordingly, alternative sprinkler designs have been proposed including rotary drive components and/or reversing mechanisms substantially encased and concealed at all times within a sprinkler housing protected against exposure to the environment. See, for example, U.S. Pat. Nos. 4,253,608 and 4,417,691 which disclose reduction gear trains driven by water turbines for rotatably driving the pop-up spray head of a sprinkler. See also U.S. Pat. No. 3,930,618 which discloses a turbine-driven impact ball arrangement for rotatably driving a pop-up sprinkler spray head. However, while these gear-drive and ball-drive sprinklers advantageously improve sprinkler capability to withstand adverse environmental conditions, the reversing mechanisms in such sprinklers generally have not been designed to prevent unauthorized tampering in a structure capable of accommodating attempted forced rotation beyond preset part-circle end limits without component breakage. Moreover, such sprinklers have experienced inconsistent drive mechanism wear rates and/or inconsistent irrigation coverage characteristics due to inadequate control of water flow as a function of pressure and spray head nozzle size.
There exists, therefore, a need for an improved rotary drive sprinkler having a controlled and preferably relatively slow rotary drive stepping speed which can be set substantially independent of water pressure and sprinkler nozzle size, and further including an improved reversing mechanism designed to prevent unauthorized tampering and to accommodate attempted tampering without significant risk of component breakage. The present invention fulfills these needs and provides further related advantages.